Warmerdam evidently was ready for the knight sac and kept blitzing his moves.
11. f3g5 Harikrishn follows his previous experience. 11... f6d5 This is absolutely forced. 12. d2e4  12... c5b4 Necessary. 13. g5f7 A new move. I wonder whether Harikrishna had prepared this when analyzing his blitz game against Ganguly. In this game, he spent some time trying to remember the lines.